Need HELP with SSL

I just tried to install SSL on my cPanel account i only have one domain on this cPanel account and IP is shared.
When i try to install SSL Cert, I get this error down below:

The certificate could not be installed on the domain “--**--.com”.
error The system failed to find an owner for the domain “--**--.com”.: The system failed to find an owner for the domain “--**--.com”.

It is important to choose a hostname that you will not be using for any account. You should choose something that will be socially acceptable, as it will appear in all mail headers. Your hostname must be a FQDN. In english, A hostname should consist of a name and a domain name. All valid hostnames should have 2 dots in them. Hostnames should never begin with "www". Hostnames should also not begin with a digit, nor end with a hyphen ("-").

It’s important that all customers accessing database or other shared services use the hostname for the service they are connecting to and not a local hostname or IP address.

This means customers accessing our shared MsSQL service should be using the hostname ‘mssql.domain.co.uk’, shared MySQL service using hostname ‘mysql.domain.co.uk’ and server names in FTP using the hostnames ‘webL.domain.co.uk’ (where L is the number of the Linux web server) or ‘winW.domain.co.uk’ (where W is the number of the Windows web server).